Soft served frozen yoghurt has become very popular in the last few years, particularly due to its ice cream like taste, yet low cholesterol content. The original cost of a "soft-serve" dispenser is in the range of 5 to 15 thousand dollars, ranging from single flavor counter-top models, to dual flavor floor models. These machines need frequent time consuming discharging and cleaning. These machines are also complex and are not without malfunction.
It is therefore desirable to devise a system costing a small fraction of the state of the art system, and provide a large number of flavors, that requires a small fraction of the present floor-space, that is easy to clean, stores the feed stock for several weeks, operates rapidly, and produces substantially the same quality product as the state of the art "soft-serve" machines. It is also desirable to accurately meter, to maintain feed-stock density, and to chop and mix in solid flavoring additives, and to require considerably less electric power; said apparatus should also be exceedingly simple to operate, and should be substantially free from malfunction.
There have been a relatively few (non refrigerated) conical screw operated frozen confection mixer extruders on the market for decades, that attempted to accomplish the above tasks, but for various operational reasons they have not become universally accepted.
The subject piston and cylinder extruder with a rotating agitator and a refrigerated pre-form loading system, can substantially meet the above requirements, except for the speed of operation. Cycle time is about equal to that of "scooping" cones.
At the present time, aggregate flavoring additions are typically placed on the top of the extruded frozen confection. It is desirable to mix fresh fruit, cookies, and candy bars into the base confection. This can be achieved with rotating and stationary cutters in said extrusion cup. The resulting confection is far superior in taste and consistency to any prior art frozen confection, since the fruit additions remain fresh, not frozen, and the cookie additions remain crisp, not soggy, as in pre-mixed frozen confections.
The Mixing Orifice Extruder produces a rich creamy product, since any residual ice crystals are broken up by a milling action, between the cutter-sweeper and the bottom of the extrusion cup. This action is similar to the action of the "drum and scraper" in a batch freezer, upon which the art of ice cream making is based on.
The Mixing Orifice Extruder was not intended to produce a homogeneous baby food like product, rather it will produce a "swirl" or "large aggregate" filled product. The flavor of a "large aggregate" filled product is much more intense than that of the same ingredients homogenized. The reason for this is, that as soon as the taste buds are "contaminated" with the pure aggregate, that intense taste will be retained at a high level long enough, till the next piece of aggregate is chewed up, and so on. A homogeneous soft-serve product may be obtained by feeding frozen homogeneous feed-stock into the extruder.
This extrusion may also be served on cones, since additions are mixed in, and will not fall off like aggregate toppings do.
The operation of this frozen confection "piston and cylinder" extruder is not critical, as far as over-softening of the product is concerned. The piston compression adds essentially no turbulence (or heat) to the charge; the only turbulence occurs at the extrusion orifice, which is slight. A separately driven agitator is needed only to soften the charge. Consequently, the Mixing Orifice Extruder needs only a 1/20 HP motor to drive the agitator, and has a relatively wide "time window" for the mixing and extruding process. With screw extruders, a significant amount of turbulence (heat generation) occurs along the entire length of the screw. Consequently, frozen confection screw extruders typically need a 1/2 to 3/4 HP motor to drive the screw; at this power input the (non-refrigerated) process must be completed in a few seconds, or "melt-down" will occur.
The cost of the ingredients of frozen yoghurt, are about 60% that of premium (hard) ice cream; yet yoghurt is selling for about the same price as premium ice cream. The main reason for this is the amortization cost, of the large number of expensive single flavor soft-serve dispensing equipment needed. A new yoghurt shop, utilizing the Mixing Orifice Extruder, should be able to reduce the selling price by up to about half of the present price, and put out a more versatile and better product.
This invention is an improvement to the device in my U.S. Pat. No. 4,668,561, "Confection Mixing Chopping and Extruding Apparatus", issued May 26, 1987, and to the apparatus described in my co-pending application, Ser. No. 07/090,702, filed Aug. 27, 1987, now U.S. Pat. No. 4,861,255, "Mixing Orifice Extruder".